1/*
2 * rtp.c
3 *
4 * library functions for the real-time transport protocol
5 *
6 * David A. McGrew
7 * Cisco Systems, Inc.
8 */
9
10
11#include "rtp_priv.h"
12
13#include <stdio.h>
14#include <string.h>
15
16#include <sys/types.h>
17#ifdef HAVE_SYS_SOCKET_H
18# include <sys/socket.h>
19#endif
20
21#define PRINT_DEBUG    0    /* set to 1 to print out debugging data */
22#define VERBOSE_DEBUG  0    /* set to 1 to print out more data      */
23
24unsigned int
25rtp_sendto(rtp_sender_t sender, const void* msg, int len) {
26  int octets_sent;
27  err_status_t stat;
28  int pkt_len = len + RTP_HEADER_LEN;
29
30  /* marshal data */
31  strncpy(sender->message.body, msg, len);
32
33  /* update header */
34  sender->message.header.seq = ntohs(sender->message.header.seq) + 1;
35  sender->message.header.seq = htons(sender->message.header.seq);
36  sender->message.header.ts = ntohl(sender->message.header.ts) + 1;
37  sender->message.header.ts = htonl(sender->message.header.ts);
38
39  /* apply srtp */
40  stat = srtp_protect(sender->srtp_ctx, &sender->message.header, &pkt_len);
41  if (stat) {
42#if PRINT_DEBUG
43    fprintf(stderr, "error: srtp protection failed with code %d\n", stat);
44#endif
45    return -1;
46  }
47#if VERBOSE_DEBUG
48  srtp_print_packet(&sender->message.header, pkt_len);
49#endif
50  octets_sent = sendto(sender->socket, (void*)&sender->message,
51		       pkt_len, 0, (struct sockaddr *)&sender->addr,
52		       sizeof (struct sockaddr_in));
53
54  if (octets_sent != pkt_len) {
55#if PRINT_DEBUG
56    fprintf(stderr, "error: couldn't send message %s", (char *)msg);
57    perror("");
58#endif
59  }
60
61  return octets_sent;
62}
63
64unsigned int
65rtp_recvfrom(rtp_receiver_t receiver, void *msg, int *len) {
66  int octets_recvd;
67  err_status_t stat;
68
69  octets_recvd = recvfrom(receiver->socket, (void *)&receiver->message,
70			 *len, 0, (struct sockaddr *) NULL, 0);
71
72  /* verify rtp header */
73  if (receiver->message.header.version != 2) {
74    *len = 0;
75    return -1;
76  }
77
78#if PRINT_DEBUG
79  fprintf(stderr, "%d octets received from SSRC %u\n",
80	  octets_recvd, receiver->message.header.ssrc);
81#endif
82#if VERBOSE_DEBUG
83  srtp_print_packet(&receiver->message.header, octets_recvd);
84#endif
85
86  /* apply srtp */
87  stat = srtp_unprotect(receiver->srtp_ctx,
88			&receiver->message.header, &octets_recvd);
89  if (stat) {
90    fprintf(stderr,
91	    "error: srtp unprotection failed with code %d%s\n", stat,
92	    stat == err_status_replay_fail ? " (replay check failed)" :
93	    stat == err_status_auth_fail ? " (auth check failed)" : "");
94    return -1;
95  }
96  strncpy(msg, receiver->message.body, octets_recvd);
97
98  return octets_recvd;
99}
100
101int
102rtp_sender_init(rtp_sender_t sender,
103		int socket,
104		struct sockaddr_in addr,
105		unsigned int ssrc) {
106
107  /* set header values */
108  sender->message.header.ssrc    = htonl(ssrc);
109  sender->message.header.ts      = 0;
110  sender->message.header.seq     = (uint16_t) rand();
111  sender->message.header.m       = 0;
112  sender->message.header.pt      = 0x1;
113  sender->message.header.version = 2;
114  sender->message.header.p       = 0;
115  sender->message.header.x       = 0;
116  sender->message.header.cc      = 0;
117
118  /* set other stuff */
119  sender->socket = socket;
120  sender->addr = addr;
121
122  return 0;
123}
124
125int
126rtp_receiver_init(rtp_receiver_t rcvr,
127		  int socket,
128		  struct sockaddr_in addr,
129		  unsigned int ssrc) {
130
131  /* set header values */
132  rcvr->message.header.ssrc    = htonl(ssrc);
133  rcvr->message.header.ts      = 0;
134  rcvr->message.header.seq     = 0;
135  rcvr->message.header.m       = 0;
136  rcvr->message.header.pt      = 0x1;
137  rcvr->message.header.version = 2;
138  rcvr->message.header.p       = 0;
139  rcvr->message.header.x       = 0;
140  rcvr->message.header.cc      = 0;
141
142  /* set other stuff */
143  rcvr->socket = socket;
144  rcvr->addr = addr;
145
146  return 0;
147}
148
149int
150rtp_sender_init_srtp(rtp_sender_t sender, const srtp_policy_t *policy) {
151  return srtp_create(&sender->srtp_ctx, policy);
152}
153
154int
155rtp_receiver_init_srtp(rtp_receiver_t sender, const srtp_policy_t *policy) {
156  return srtp_create(&sender->srtp_ctx, policy);
157}
158
159rtp_sender_t
160rtp_sender_alloc() {
161  return (rtp_sender_t)malloc(sizeof(rtp_sender_ctx_t));
162}
163
164rtp_receiver_t
165rtp_receiver_alloc() {
166  return (rtp_receiver_t)malloc(sizeof(rtp_receiver_ctx_t));
167}
168